如何修复单选按钮不显示消息框

Question

I want to make radio button and when I click button save and then my radio button not selected it can appear some message box.

 private void btnSimpan_Click(object sender, EventArgs e) { try { DataPembeli p = new DataPembeli(); p.Pembeli = txtPembeli.Text; p.AlamatKirim = txtAlamat.Text; p.Kuantitas = (int)kuantitasItem.Value; p.TglPesan = dtTglPesanan.Value; p.HasAsuransi = chkAsuransi.Checked; p.ItemOrdered= cmbItem.Text; foreach (Control c in grpbxMetodePengiriman.Controls) { if (c is RadioButton) { RadioButton rb = (RadioButton)c; if (rb.Checked) { p.MetodePengiriman = rb.Text; break; } } else { p.MetodePengiriman = "0"; break; }

Answer 1

You appear to be saying that you want to make sure that the user has checked a RadioButton in a group. If so, the best way is to use LINQ to get all the RadioButtons in the container and see if any are checked, eg

if (myContainer.Controls.OfType<RadioButton>().Any(rb => rb.Checked))
{
    // A RadioButton in myContainer has been checked.
}

If you actually want to get the checked RadioButton and use it then you can do this:

var checkedRadioButton = myContainer.Controls.OfType<RadioButton>().FirstOrDefault(rb => rb.Checked)

if (checkedRadioButton == null)
{
    // No RadioButton is checked.
}
else
{
    // Use checkedRadioButton here.
}

Based on your code, you could probably do this:

p.MetodePengiriman = myContainer.Controls
                                .OfType<RadioButton>()
                                .FirstOrDefault(rb => rb.Checked)
                                ?.Text ?? "0";

FirstOrDefault will either return a RadioButton reference or null . If the former, the Text property of that control will be used. If the latter, the ?. operator will cause the whole expression to evaluate to null and then the "0" will be used instead.